Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
  • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L3/00—Gaseous fuels; Natural gas; Synthetic natural gas obtained by processes not covered by subclass C10G, C10K; Liquefied petroleum gas
  • C10L3/06—Natural gas; Synthetic natural gas obtained by processes not covered by C10G, C10K3/02 or C10K3/04
  • C10L3/10—Working-up natural gas or synthetic natural gas
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
  • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
  • F25J1/0221—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process using the cold stored in an external cryogenic component in an open refrigeration loop
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
  • F25J1/0002—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the fluid to be liquefied
  • F25J1/0022—Hydrocarbons, e.g. natural gas
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
  • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
  • F25J1/0243—Start-up or control of the process; Details of the apparatus used; Details of the refrigerant compression system used
  • F25J1/0244—Operation; Control and regulation; Instrumentation
  • F25J1/0254—Operation; Control and regulation; Instrumentation controlling particular process parameter, e.g. pressure, temperature
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J2205/00—Processes or apparatus using other separation and/or other processing means
  • F25J2205/02—Processes or apparatus using other separation and/or other processing means using simple phase separation in a vessel or drum
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J2205/00—Processes or apparatus using other separation and/or other processing means
  • F25J2205/30—Processes or apparatus using other separation and/or other processing means using a washing, e.g. "scrubbing" or bubble column for purification purposes
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J2205/00—Processes or apparatus using other separation and/or other processing means
  • F25J2205/90—Mixing of components
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J2210/00—Processes characterised by the type or other details of the feed stream
  • F25J2210/04—Mixing or blending of fluids with the feed stream
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J2210/00—Processes characterised by the type or other details of the feed stream
  • F25J2210/62—Liquefied natural gas [LNG]; Natural gas liquids [NGL]; Liquefied petroleum gas [LPG]
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J2215/00—Processes characterised by the type or other details of the product stream
  • F25J2215/02—Mixing or blending of fluids to yield a certain product
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J2220/00—Processes or apparatus involving steps for the removal of impurities
  • F25J2220/60—Separating impurities from natural gas, e.g. mercury, cyclic hydrocarbons
  • F25J2220/62—Separating low boiling components, e.g. He, H2, N2, Air
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J2235/00—Processes or apparatus involving steps for increasing the pressure or for conveying of liquid process streams
  • F25J2235/60—Processes or apparatus involving steps for increasing the pressure or for conveying of liquid process streams the fluid being (a mixture of) hydrocarbons
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J2240/00—Processes or apparatus involving steps for expanding of process streams
  • F25J2240/40—Expansion without extracting work, i.e. isenthalpic throttling, e.g. JT valve, regulating valve or venturi, or isentropic nozzle, e.g. Laval
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J2290/00—Other details not covered by groups F25J2200/00 - F25J2280/00
  • F25J2290/62—Details of storing a fluid in a tank

Definitions

• This invention relates to a process for producing pressurized methane-rich liquid from a methane-rich gas and, more particularly, to a process for producing pressurized liquid natural gas (PLNG) from natural gas.
• PLNG pressurized liquid natural gas
• LNG liquefied natural gas
• the liquefaction plant is made up of several basic systems, including gas treatment to remove impurities, liquefaction, refrigeration, power facilities, and storage and ship loading facilities.
• LNG refrigeration systems are expensive because so much refrigeration is needed to liquefy natural gas.
• a typical natural gas stream enters a LNG plant at pressures from about 4,830 kPa (700 psia) to about 7,600 kPa (1,100 psia) and temperatures from about 20°C (68°F) to about 40°C (104°F).
• Natural gas compositions at atmospheric pressure will typically liquefy in the temperature range between about -165°C (-265°F) and -155°C (-247°F). This significant reduction in temperature requires substantial refrigeration duty. It has been recently proposed to transport natural gas at temperatures above -112°C (-170°F) and at pressures sufficient for the liquid to be at or below its bubble point temperature.
• the pressure of the natural gas at temperatures above -112°C (-170°F) will be between about 1,380 kPa (200 psia) and about 4,500 kPa (650 psia).
• This pressurized liquid natural gas is referred to as PLNG to distinguish it from LNG, which is transported at near atmospheric pressure and at a temperature of about -162°C (-260°F).
• the production of PLNG requires significantly less refrigeration than that required for the production of LNG since PLNG can be more than 50°C warmer than conventional LNG at atmospheric pressure. Examples of processes for manufacturing PLNG are disclosed in U.S. patent applications 09/099262, 09/099590, and 09/099589 and in U.S. provisional application 60/079642. In view of the substantial economic benefits associated with making and transporting PLNG, a continuing need exists for improved processes for producing PLNG.
• An improved process for producing from a pressurized methane- rich gas stream a pressurized methane-rich liquid stream having a temperature above -112°C (-170°F) and having a pressure sufficient for the liquid to be at or below its bubble point.
• a methane-rich liquid stream having a temperature below about -155°C (-247°F) is supplied and its pressure is increased.
• a pressurized methane-rich gas to be liquefied is supplied and introduced to the pressurized methane-rich liquid stream at a rate that produces a methane-rich liquid stream having a temperature above -112°C (-170°F) and a pressure sufficient for the liquid to be at or below its bubble point.
• a pressurized liquid natural gas is produced by supplying LNG having a pressure near atmospheric pressure and pumping the LNG to the desired pressure of PLNG to be produced by the process. Natural gas is supplied to the process and the pressure is adjusted either up or down, if needed, to be at essentially the same pressure as the pressurized LNG. Depending on the available pressure of the natural gas, its pressure can be increased by a compression means or decreased by an expansion device such as a Joule-Thomson valve or turboexpander. The pressurized natural gas is then mixed with the pressurized LNG at a rate that produces PLNG having a temperature above -112°C (-170°F) and a pressure sufficient for the resulting liquid to be at or below its bubble point.
• PLNG pressurized liquid natural gas
• the natural gas may optionally be cooled before it is mixed with the pressurized PLNG by any suitable cooling means.
• the natural gas may be cooled by indirect heat exchange with an external cooling medium, by an expansion device that reduces the pressure of the natural gas, or by heat exchange with the pressurized LNG.
• the mixture produced by the mixing of the pressurized LNG and the pressurized natural gas may optionally be passed through a phase separator to remove any gas that remains unliquefied after the mixing.
• the liquid withdrawn from the separator is then passed to a suitable storage means for storage at a temperature above -112°C (-170°F) and a pressure sufficient for it to be at or below its bubble point.
• Fig. 1 is a schematic diagram of one embodiment of the present invention in which pressurized natural gas is combined with pressurized LNG to produce PLNG.
• Fig. 2 is a schematic diagram of another embodiment of the present invention similar to the embodiment of Fig. 1 except that pressurized LNG and pressurized natural gas are passed through a heat exchanger before being combined to produce PLNG.
• Fig. 3 is a schematic diagram of still another embodiment of the invention similar to the embodiment of Fig. 1 except that liquid mixture resulting from mixing of pressurized LNG and pressurized natural gas is passed to a phase separator to remove any unliquefied gas.
• the process of this invention produces a pressurized methane-rich liquid product stream having a temperature above -112°C (-170°F) and having a pressure sufficient for the liquid to be at or below its bubble point.
• This liquid product is sometimes referred to in this description as PLNG.
• PLNG is made by pressurizing a methane-rich liquid, preferably liquid natural gas (LNG) at or near atmospheric pressure, to the desired pressure of the PLNG product to be produced by the process and introducing to the pressurized methane-rich liquid a pressurized methane-rich gas, preferably pressurized natural gas.
• LNG liquid natural gas
• the pressurized methane-rich liquid is warmed by the pressurized natural gas and the methane-rich gas is liquefied by the pressurized methane-rich liquid to produce PLNG having a temperature above -112°C (-170°F) and having a pressure sufficient for the liquid to be at or below its bubble point.
• bubble point means the temperature and pressure at which PLNG begins to convert to gas. For example, if a certain volume of PLNG is held at constant pressure, but its temperature is increased, the temperature at which bubbles of gas begin to form in the PLNG is the bubble point. Similarly, if a certain volume of PLNG is held at constant temperature but the pressure is reduced, the pressure at which gas begins to form defines the bubble point. At the bubble point, the liquefied gas is saturated liquid.
• the bubble point pressure of the natural gas at temperatures above -112°C will be between about 1,380 kPa (200 psia) and about 4,500 kPa (650 psia).
• temperatures above -112°C 170°F
• the bubble point pressure of the natural gas at temperatures above -112°C will be between about 1,380 kPa (200 psia) and about 4,500 kPa (650 psia).
• persons skilled in the art can determine the bubble point pressure.
• LNG from any suitable source is supplied to line 10 and is passed to a suitable pump 20.
• the LNG can be supplied for example by a pipeline from a LNG plant, from a stationary storage container, or from a carrier such as one or more containers on a truck, barge, railcar, or ship.
• the LNG will typically have a temperature below about -155°C (-247°F) and more typically will have a temperature of about -162°C (-260°F) and will have a pressure at near atmospheric pressure.
• Pump 20 increases the pressure of the LNG to a predetermined level, which is the desired pressure of the PLNG to be produced by the process of this invention.
• the pressure of the PLNG product is sufficient for the liquid to be at or below its bubble point.
• the pressure of the PLNG product will therefore depend on the temperature and composition of the PLNG product.
• the pressure of the liquid exiting pump 20 through line 11 will typically will have a pressure above 1,380 kPa (200 psia) and more typically will have a pressure ranging between about 2,400 kPa (350 psia) and 3,800 kPa (550 psia).
• Natural gas is supplied to line 12 from any suitable source.
• the natural gas suitable for the process of this invention may comprise natural gas obtained from a crude oil well (associated gas) or from a gas well (non-associated gas).
• the composition of natural gas can vary significantly.
• a natural gas stream contains methane (Ci) as a major component.
• the natural gas will typically also contain ethane (C 2 ), higher hydrocarbons (C 3+ ), and minor amounts of contaminants such as water, carbon dioxide (CO 2 ), hydrogen sulfide, nitrogen, butane, hydrocarbons of six or more carbon atoms, dirt, iron sulfide, wax, and crude oil.
• the solubilities of these contaminants vary with temperature, pressure, and composition.
• the natural gas stream in line 12 has been suitably treated to remove sulfides and carbon dioxide and dried to remove water using conventional and well-known processes to produce a "sweet, dry" natural gas stream. If the natural gas feed stream contains heavy hydrocarbons which could freeze out during mixing with the pressurized LNG or if the heavy hydrocarbons are not desired in the PLNG, the heavy hydrocarbon can be removed by a conventional fractionation process at any point in the process of this invention before the natural gas is mixed with the pressurized LNG.
• the natural gas feed stream 12 will typically enter the process at a pressure above about 1,380 kPa (200 psia), and more typically will enter at a pressure above about 4,800 kPa (700 psia), and will typically be at ambient temperature; however, the natural gas can be at different pressures and temperatures, if desired, and the process can be modified accordingly.
• natural gas in line 12 is below the pressure of pressurized LNG in line 11, the natural gas can be pressurized by a suitable compression means (not shown), which may comprise one or more compressors.
• a suitable compression means not shown
• the natural gas stream supplied to line 12 has a pressure at least as high as the pressure of pressurized LNG in line 11.
• Pressurized natural gas in line 12 is preferably passed to a flow control device 21 suitable for controlling flow and/or reducing pressure between line 12 and line 13.
• flow control device 21 can be in the form of a turboexpander, a Joule-Thomson valve, or a combination of both, such as, for example, a Joule-Thomson valve and a turboexpander in parallel, which provides the capability of using either or both the Joule-Thomson valve and the turboexpander simultaneously.
• an expanding device such a Joule-Thomson valve or a turboexpander to expand the natural gas to reduce its pressure, the natural gas is also cooled. Cooling of the natural gas is desirable, although not a required step in the process, because decreasing the temperature of the natural gas before it is mixed with the pressurized LNG can increase the amount of PLNG produced.
• the additional cooling means may comprise one or more heat exchange systems cooled by conventional refrigeration systems or one or more expansion devices such as Joule-Thomson valves or turboexpanders.
• the optimum cooling system would depend on the availability of refrigeration cooling, space limitations, if any, environmental and safety considerations, and the desired amount of PLNG to be produced.
• persons skilled in the art of gas processing can select a suitable cooling system taking into account the operating circumstances of the liquefaction process.
• the methane-rich liquid in line 11 and the natural gas of line 13 are combined or mixed to produce a combined liquid stream in line 14.
• the liquid in line 14 is directed to a suitable storage means 23 such as a stationary storage container or a suitable carrier such as a ship, barge, submarine vessel, railroad tank car, or truck.
• a suitable storage means 23 such as a stationary storage container or a suitable carrier such as a ship, barge, submarine vessel, railroad tank car, or truck.
• PLNG in storage means 23 will have a temperature above about -112°C (-170°F) and a pressure sufficient for the liquid to be at or below its bubble point.
• Fig. 2 illustrates another embodiment of the invention and in this and the embodiments illustrated in Figs. 1 and 3, the parts having like numerals have the same process functions. Those skilled in the art will recognize, however, that the process equipment from one embodiment to another may vary in size and capacity to handle different fluid flow rates, temperatures, and compositions.
• the embodiment illustrated in Fig. 2 is similar to the embodiment illustrated in Fig. 1 except that in Fig. 2 pressurized LNG in line 11 and pressurized gas in line 13 are both passed to a conventional heat exchanger 22 to heat the pressurized LNG in line 11 and to further cool natural gas in line 13 before the pressurized LNG and the natural gas are combined (line 14).
• the LNG By cooling the natural gas against the pressurized LNG in the heat exchanger 22, the LNG is warmed to near the temperature of the pressurized LNG before the natural gas and the pressurized LNG are mixed. This could reduce the potential for formation of solids from components in the feed natural gas at the colder (-162°C) LNG temperature.
• the flow rate of methane-rich fluids passing through lines 11 and/or 13 should be controlled to produce the desired temperature of PLNG.
• the temperature of the PLNG is to be above -112°C as a minimum temperature and below its critical temperature as a maximum temperature.
• Natural gas which is predominantly methane, cannot be liquefied at ambient temperature by simply increasing the pressure, as is the case with heavier hydrocarbons used for energy purposes.
• the critical temperature of methane is -82.5°C (-116.5°F). This means that methane can only be liquefied below that temperature regardless of the pressure applied. Since natural gas is a mixture of liquid gases, it liquefies over a range of temperatures.
• the critical temperature of natural gas is typically between about -85°C (-121°F) and -62 °C (-80°F). This critical temperature will be the theoretical maximum temperature of PLNG in PLNG storage containers, but the preferred storage temperature will be several degrees below the critical temperature and at a lower pressure than its critical pressure.
• the resulting mixture in line 14 will be above its bubble point and at least part of the mixture will be in a gaseous state.
• the temperature of the combined stream (line 14) will be below -112°C (-170°F). Avoiding temperatures below -112°C ( ⁇ 170°F) is desirable to prevent exposing the materials used in handling and storage of PLNG to temperatures below the design temperature of the materials.
• Fig. 3 illustrates another embodiment of the invention, which is similar to the embodiment illustrated in Fig. 1 except that the combined pressurized LNG and pressurized natural gas in line 14 is passed to a conventional phase separator 24 to removed any unliquefied gas that remains after the natural gas (line 13) is mixed with the pressurized LNG (line 11).
• a conventional phase separator 24 to removed any unliquefied gas that remains after the natural gas (line 13) is mixed with the pressurized LNG (line 11).
• some of the gas after being mixed with pressurized LNG may remain in a gaseous state.
• the gas may not completely liquefy at the desired temperature and pressure if the natural gas contains significant levels of a component having a lower boiling point than methane, such as nitrogen.
• the gas removed through line 16 from separator 24 will be enriched in nitrogen and the liquid exiting through line 15 will be leaner in nitrogen.
• the gas stream (line 16) exiting the separator 24 may be removed from the process for use as fuel or for further processing.
• the PLNG exiting the separator 24 is passed through line 15 to a storage means 23.
• the process can be used to produce more liquid natural gas than the design capacity of a LNG plant with minimal additional equipment.
• LNG produced by a conventional LNG plant can provide the refrigeration needed to liquefy natural gas, thereby substantially increasing the amount of liquid natural gas that can be produced as a product.
• the remaining capacity of the LNG plant could be used to supply the LNG to the process of this invention.
• part or all of the LNG delivered by ship to an import terminal may be supplied to the process of this invention to produce PLNG for subsequent distribution.
• HYSYSTM available from Hyprotech Ltd. of Calgary, Canada
• other commercially available process simulation programs can be used to develop the data, including for example HYSIMTM, PROIITM, and ASPEN PLUSTM, which are familiar to those of ordinary skill in the art.
• the data presented in the Table are offered to provide a better understanding of the embodiment shown in the drawing, but the invention is not to be construed as unnecessarily limited thereto.
• the temperatures and flow rates are not to be considered as limitations upon the invention, which can have many variations in temperatures and flow rates in view of the teachings herein.
• flow control device 21 was a Joule-Thomson valve.

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• Engineering & Computer Science (AREA)
• Thermal Sciences (AREA)
• General Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• General Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Organic Chemistry (AREA)
• Filling Or Discharging Of Gas Storage Vessels (AREA)
• Separation By Low-Temperature Treatments (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Catching Or Destruction (AREA)

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• 1999
  • 1999-11-22 MY MYPI99005080A patent/MY123311A/en unknown
  • 1999-11-23 GC GCP1999378 patent/GC0000083A/xx active
  • 1999-12-07 TN TNTNSN99231A patent/TNSN99231A1/fr unknown
  • 1999-12-13 TW TW088121821A patent/TW514704B/zh not_active IP Right Cessation
  • 1999-12-16 US US09/464,986 patent/US6237364B1/en not_active Expired - Fee Related
  • 1999-12-16 PE PE1999001266A patent/PE20001103A1/es not_active Application Discontinuation
  • 1999-12-17 CO CO99079011A patent/CO5111062A1/es unknown
  • 1999-12-17 MX MXPA01007045A patent/MXPA01007045A/es not_active Application Discontinuation
  • 1999-12-17 ES ES200150062A patent/ES2222773B1/es not_active Withdrawn - After Issue
  • 1999-12-17 CA CA002358470A patent/CA2358470A1/en not_active Abandoned
  • 1999-12-17 OA OA1200100184A patent/OA11818A/en unknown
  • 1999-12-17 TR TR2001/02052T patent/TR200102052T2/xx unknown
  • 1999-12-17 GE GE4518A patent/GEP20043414B/en unknown
  • 1999-12-17 AR ARP990106500A patent/AR021881A1/es active IP Right Grant
  • 1999-12-17 RU RU2001122814/06A patent/RU2224192C2/ru not_active IP Right Cessation
  • 1999-12-17 KR KR1020017008902A patent/KR20010089834A/ko not_active Application Discontinuation
  • 1999-12-17 BR BR9916909-6A patent/BR9916909A/pt active Search and Examination
  • 1999-12-17 WO PCT/US1999/030256 patent/WO2000042348A1/en not_active Application Discontinuation
  • 1999-12-17 EP EP99966437A patent/EP1169601A4/de not_active Withdrawn
  • 1999-12-17 GB GB0118528A patent/GB2363636B/en not_active Expired - Fee Related
  • 1999-12-17 AU AU21972/00A patent/AU756734B2/en not_active Ceased
  • 1999-12-17 UA UA2001085706A patent/UA57872C2/uk unknown
  • 1999-12-17 ID IDW00200101757A patent/ID29787A/id unknown
  • 1999-12-17 JP JP2000593886A patent/JP2002535419A/ja active Pending
  • 1999-12-17 CN CN99815613A patent/CN1102215C/zh not_active Expired - Fee Related
  • 1999-12-17 YU YU50501A patent/YU49434B/sh unknown
  • 1999-12-18 EG EG161799A patent/EG22006A/xx active
• 2001
  • 2001-07-12 NO NO20013466A patent/NO20013466L/no not_active Application Discontinuation
  • 2001-08-09 BG BG105798A patent/BG105798A/xx unknown

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